Writing SEO Friendly URL using HttpHandlers in ASP.NET

In general, it is recommend to not use querystring in the URL as search engines don't rank those pages well and give very low priority. To avoid querystring there are several third party component that can be used like ISAPI, URL rewriter.

Introduction

HttpHandler is the low level Request and Response API to service incoming HTTP requests. All handlers implement the IHttpHandler interface. There is no need to use any extra namespace to use it as it contains in the System.Web namespace. Handlers are somewhat analogous to Internet Server Application Programming Interface (ISAPI) extensions.

Background

In this article, I am going to explain how to use HttpHandler to create a SEO friendly as well as user friendly URL. During this article, I will create two .aspx file, one HandlerUrl.cs class file. I am assuming here that I have to show a different article based on the id I get from the request. But I will not get the id as querystring but as part of the name of the page like article1.aspx or article2.aspx. Here 1 and 2 is my article id. I will extract it and send into my page (showarticle.aspx) using Server.Transfer method so that my URL in the browser will be like article1.aspx but internally it will be served as showarticle.aspx?id=1.

Step 1 - Create an HttpHandler

Right click your App_Code folder and add a .cs file named HandlerUrl.cs and write the following code:

namespace UrlHandlerNameSpace
{
///<summary>/// Demo url HttpHandler
///</summary>publicclass DemoUrlHandler: IHttpHandler
{
///<summary>/// Process my request
///</summary>///<paramname="context"></param>publicvoid ProcessRequest(HttpContext context)
{
// get the requested page name like article1.aspxstring strUrl = System.IO.Path.GetFileName(context.Request.RawUrl.ToString());
// get the page name without extension eg. "article1"int len = strUrl.IndexOf(".");
// as the length of "article" is 7 int sep = 7;
// subtract the length of "article" word from the complete length // of the page name to get the // length of the id, as it may be 1, 100, 50000 // (1 character lonr or 3 chars long or may be 5 chars long)
len -= sep;
// now get the exact idstring id = strUrl.Substring(sep, len);
// Now transfer the request to the actual page that will show the article // based on the id
HttpContext.Current.Server.Transfer("~/urlhandler/showArticle.aspx?id=" + id);
}
publicbool IsReusable
{
get
{
returntrue;
}
}
}
}

As you can see, I have inherited IHttpHandler interface into DemoUrlHandler class file so I will have to implement two methods of it - ProcessRequest and IsReusable. ProcessRequest is the method that handles my request and sends the request using Server.Transfer to the showArticle.aspx specifying the id of as the querystring. I have done some calculations to extract the id from the name of the requested page.

verb specifies whether the request will serve only GET or POST or all requests (*), I have specified that this handler should serve all kinds of the request.

path specifies the path, when requested my handler should take action. In this case, I have specified that my handler should act when my requested URL contains "article/article*.aspx". You can specify wild card characters too, like I have specified here. Notice "*" between "article" and ".aspx" characters. It means that I am instructing that my handler should act irrespective of whatever characters come after "article" word in my page name.

Step 3 - Create a Page (default.aspx) to List Different URLs

For testing purposes, I have created a default.aspx page that will list different URLs like article1.aspx, article2.aspx, article3.aspx, etc. as displayed in the picture below:

Step 4 - Create a Page (showArticle.aspx) to Show Articles

This page will show my article based on the querystring passed to it from my handler.

protectedvoid Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
if (Request["id"] != null)
{
// Call your function to get data from database based on the id// This is just a demo application so I am writing title based on the idstring title = "Title for Article " + Request["id"].ToString();
litPageTitle.Text = title;
this.Title = title;
}
}
}

Now make the default.aspx page as startup page and run your demo project. You should see the page like default.aspx above, try clicking one of the URLs and you will see the corresponding page (below image). Notice the address bar in the picture below. The URL is "/article/article8.aspx" but internally this page is being served by showarticle.aspx with querystring as 8 (/urlhandler/showarticle.aspx?id=8). In this way, you are not showing querystring in the browser, your URL is neat and clean. This page will be understood by the search engines as a complete stand along page rather than a page with different querystring value and will be given much more weightage than a single page with different querystring value.

Conclusion

To form a SEO friendly and user friendly URL, we don't need to use any third party component. Using ASP.NET HttpHandler, we can do it easily by writing a small amount of code.

This is not a good solution to the url rewriting problem. You are transfering to another page before the Session has been initialized in global.asax. You should instead catch the Application_BeginRequest event and use Contex.ReWritePath there